Fabrication of double barrier structures in single layer c-Si–QDs/a-SiOx films for realization of energy selective contacts for hot carrier solar cells

Thin films of c-Si–QDs embedded in an a-SiOx dielectric matrix forming arrays of double barrier structures have been fabricated by reactive rf-magnetron sputtering at ∼400 °C, without post-deposition annealing. The formation of larger size c-Si–QDs of reduced number density in homogeneous distributi...

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Bibliographic Details
Published in:Journal of applied physics 2017-01, Vol.121 (4)
Main Authors: Kar, Debjit, Das, Debajyoti
Format: Article
Language:English
Subjects:
Applied physics
Barriers
Carrier mobility
Current carriers
Magnetron sputtering
Photovoltaic cells
Plasma pressure
Solar cells
Thin films
Transmission electron microscopy
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Summary:Thin films of c-Si–QDs embedded in an a-SiOx dielectric matrix forming arrays of double barrier structures have been fabricated by reactive rf-magnetron sputtering at ∼400 °C, without post-deposition annealing. The formation of larger size c-Si–QDs of reduced number density in homogeneous distribution within a less oxygenated a-SiOx matrix at higher plasma pressure introduces systematic widening of the average periodic distance between the adjacent ‘c-Si–QDs in a-SiOx’, as obtained by X-ray reflectivity and transmission electron microscopy studies. A wave-like pattern in the J-E characteristics identifies the formation of periodic double-barrier structures along the path of the movement of charge carriers across the QDs and that those are originated by the a-SiOx dielectric matrix around the c-Si–QDs. A finite distribution of the size of c-Si–QDs introduces a broadening of the current density peak and simultaneously originates the negative differential resistance-like characteristics, which have suitable applications in the energy selective contacts that act as energy filters for hot carrier solar cells. A simple yet effective process technology has been demonstrated. Further initiative on tuning the energy selectivity by reducing the size and narrowing the size-distribution of Si–QDs can emerge superior energy selective contacts for hot carrier solar cells, paving ground for accomplishing all-Si solar cells.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4974739